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Charlotte Gainsbourg2

It's not often that a piece of music can make your hair stand on end. Listening to the title track on Charlotte Gainsbourg's new album, IRM, I have that very sensation. Beneath Charlotte's breathy vocals are the unmistakable metallic clangs, thuds and blarings made by a magnetic resonance imaging (MRI) scanner. The sound takes me straight back to the tubular coffin where I endured a claustrophobic hour a few weeks back. I actually have to turn the CD off.

I like the noise,' says Charlotte simply, with the too-perfect diction that marks out a foreigner. I almost think I love it. The sounds are very aggressive, but I had to find a way of enjoying myself. I almost got to know the sequence of noises; I'd be waiting for the hammer sound, for the drill it was like going on a journey.'

We are sitting in the shabby-chic lounge of The Portobello Hotel. Charlotte, 38, looks effortlessly cool dressed down in skinny black jeans and scuffed suede boots. As the daughter of English rose actress Jane Birkin and French proto-punk singer-songwriter Serge Gainsbourg, looking effortlessly cool is, of course, her birthright. But she also appears exhausted, her small face under its curtain of dark hair painfully thin.

The past three years have been difficult. She was waterskiing on holiday in America in the summer of 2007 when she fell on her head. I didn't think anything of it,' she says. I didn't feel anything.' But the fall had caused a slow bleed into her brain. Six weeks later, she was due to appear at the Venice Film Festival to present Todd Haynes' Bob Dylan biopic I'm Not There, in which she played one of Dylan's wives, when she was crippled by an appalling headache that wouldn't go away.

I was crying with pain, but I just thought I was having a migraine,' she says. Under heavy medication I could stand up and talk, so I coped for a week.' Her elder sister, the photographer Kate Barry, insisted she went for an MRI scan. I went straight from the airport to the doctor, and they took me from there directly to hospital.' Her head was so full of blood that her brain had been pushed to one side; her doctor told her she ought to have been dead or at least paralysed.

It was all such a panic that I didn't have time to be scared, though I did wave goodbye to my mother when they took me into surgery.' It was only afterwards that the terror set in. It was the first time I'd ever been scared of dying,' she says. I used to think I was quite brave and didn't care that much, but I understood that I wasn't ready. I felt a bit of a coward.' Was she afraid for herself, or for her potentially motherless children? She has two, Ben, 12, and Alice, seven. I was scared for myself,' she says honestly. That's what I didn't like about it.'

Charlotte took six months off work to recover, during which time she suffered repeated panic attacks. I became a complete hypochondriac, and each time I panicked, I went back for an MRI. I had about eight in six months. It was the only way I could reassure myself that I was fine.'

She only began to recover when she went back to work. For her convalescence, she chose a role in the controversial Danish director Lars von Trier's film Antichrist, about a grieving couple holed up in a cabin in some very frightening woods, which has been called the most shocking film in the history of the Cannes Film Festival'. Charlotte carried off the festival's Best Actress award, but the jury also awarded the director a special booby prize for misogyny – the film culminated notoriously in Charlotte performing an auto-clitoridectomy. It sounds like the sort of role calculated to bring on post-traumatic stress disorder rather than cure it, but Charlotte seems convinced it was therapeutic. I think it helped me get out of the accident and my problems. I didn't have time to think about it any more,' she says. The whole thing was surreal, weird and I was spaced out afterwards. I needed to go back to Paris every weekend to see my family but I had to keep the work very separate.'

She was desperate to unburden herself of everything that had happened on set, but her family were out of bounds – her long-term partner, Israeli-born actor-director Yvan Attal, was understandably wary of hearing what she'd been putting herself through. He read the script and was fine about it but he didn't want me to tell him the details.' She also tried to confide in American indie rocker and Scientologist Beck, with whom she collaborated on IRM. But after a while I got embarrassed. Thank God I was able to talk about it to my mother. I told her everything I did every day.' (Jane Birkin called it an extraordin-arily funny correspondence. She was saying what she was up to – like masturbating against the roots of trees.')

Returning to normal must have been rather difficult. It was strange not being able to scream all day and take my clothes off,' she agrees. I was extremely tired coming out of that, but it was very exhilarating.' Perhaps the extreme violence of the role acted as a sort of primal scream therapy, allowing her to exorcise her rage and terror. At any rate, she followed it up with IRM (French for MRI), which would seem a more recuperative project.

Charlotte and Beck already had something of a mutual fan club going before they met, thanks to their respective fathers. Beck had borrowed parts of Serge Gainsbourg's classic Ballade de Melody Nelson' for his track Paper Tiger'; she had employed his father, the composer David Campbell, to arrange the strings on 5:55, the hit 2006 album she made with Parisian band Air and our own Jarvis Cocker.

Then I had the accident, and then I had the idea of working with Beck,' she says. He asked me what I wanted and I didn't know. I just wanted to explore things with him and try as many styles as we could.' Oddly, for the first song they worked on together, Master's Hands', Beck had written the lyrics drill my brain all full of holes'; Charlotte, who describes their collaboration as alchemy', says he knew nothing about her accident and operation at the time, and apologised when he found out. Subsequently, she suggested sampling the MRI scanner noises she had learned, rather perversely, to enjoy.

They recorded the album in Beck's home studio in LA, an on-off process that took a year and a half to complete. There was something everyday about it, going there in the morning, being there with his children and sometimes mine. The casualness of it was very helpful,' says Charlotte, who admits to being so shy during the recording of 5:55 that she sang under a sheet. Usually it was just me, Beck and the sound engineer. When I was recording, very often Beck would be coming in and out pretending it wasn't important. It meant I could try things out and not judge myself. And Beck is so benevolent.'

Her favourite song on the album is Trick Pony' – because my son plays the drums,' she says. He was having fun, he didn't know we were recording him. Then Beck said, "It's a great beat!" and we used it. I was so proud.' Alice's voice has also been sampled for another song, GMT'. It's funny when we play it to them and see them blush. It's sweet.'

It's also history repeating itself. When Charlotte was just 13, she duetted with her father on Lemon Incest', a song that included the lyric the love that we will never make is the purest, the most tender' This was accompanied by a video in which the pair rolled around together on a bed. It caused a scandal that even eclipsed that of Je t'aime moi non plus', the 1969 song recorded by her parents that included Birkin simulating orgasm and was denounced by the Pope.

Didn't Charlotte ever feel resentful as a child, being thrust into controversy by her father? Not at all, no,' she says. Even though the subject was very provocative, I didn't know it was a scandal when it came out because I was in a boarding school. I was protected.' (She was more directly affected when her father burned a banknote on television; the following day, her classmates burned her schoolbooks in retaliation.)

So she's not too concerned about keeping her children out of the limelight. The more my children grow up, the more I can understand why my father did it,' she says. And we've already worked with my son; Yvan, my boyfriend, did a film called Happily Ever After and Ben played our son. We asked ourselves a lot of questions, not knowing if it was the right decision, but in the end, the pleasure we had working together, the complicity and the memories were more important than what people might say.' Does she want her children to follow in her performing footsteps? I could understand if they were tempted,' she says. I hope I'm showing them how much pleasure I get from it.'

She describes her own childhood as very square. We went to school, we went on holiday to our cottage in Normandy. We had nannies so we had a very normal life. Of course, my parents were crazy; they went out every night, and when we were leaving the house to go to school, they would be coming in from a nightclub.'

Equally surprisingly, she says her famously dishevelled father was a maniac' in his tidiness. We had our nursery, and we weren't allowed to be anywhere else. To get to our room we had to go through the sitting room but we couldn't stop. And they were very strict on what we could touch. To do the housework, you'd have to pick up the cup, polish underneath it and replace it in exactly the same spot.'

She insists her childhood was happy, but it does sound rather fraught. Perhaps that's why she threw herself into her career at an early age, heading off to Canada at the age of 12 to make her first film, Paroles et Musique, with Catherine Deneuve. I loved doing the films. I was happy doing them on my own, and I'm very grateful to my parents that they let me do them,' she says.

She has barely stopped working since, starring in some 40 films, including Jane Eyre, with William Hurt; 21 Grams, with Sean Penn; and the forthcoming A Boy and His Shoe, with Daniel Auteuil and Guillaume Canet. Although these days she admits to suffering the usual maternal guilt about spreading herself too thin, she is clearly going to carry on till she drops (just like her mother, who's still performing). I love my work,' she says. I couldn't put it aside.' This year, she's struggling to combine the demands of her album tour with a film role she's desperate to take; she's also been recruited by her friend, the designer Nicolas Ghesquière, to star in the campaign for Balenciaga's new perfume.

So will she choose the acting or the singing? I'll arrange it so I can do both,' she says. And after all, what's a mere diary clash, when even a brain haemorrhage can't slow Charlotte down?